1. Field of the Invention
This invention relates to a lubricating structure of a hydrostatic continuously variable transmission and more particularly a structure of oil path for use in ejecting lubricant oil from a transmission shaft to a rotary sliding part such as a slant plate in the hydrostatic continuously variable transmission.
2. Description of Background Art
In the prior art hydrostatic continuously variable transmission, there have been provided a plurality of diametrical lubricant oil ejection holes directed from the central oil path at the transmission shaft formed axially at the center of the transmission shaft toward the outer circumferential part of the transmission shaft in order to eject the lubricant oil from the transmission shaft to the rotary sliding part such as a slant plate and the like (for example, refer to JP-A No. 54734/2002 (FIG. 2) and JP-A No. 100909/1997 (Reference symbol 77, FIG. 2)).
The lubricant oil ejection holes are holes of relative fine diameter. As described above, arrangement of a plurality of holes of fine diameter at a thick-wall part of the transmission shaft generated a reduced productivity of the transmission, since holes with very fine diameters could not be produced, which resulted in feeding more than a requisite amount of oil. In addition, even if the hole of fine diameter could be machined, feeding of oil to an appropriate location required an increased number of holes. This was not preferable because it resulted in increasing the volume of the oil pump.